1. Clinical Neuroscience Branch, National Institute of Mental Health, Bethesda, Maryland 20205
2. Clinical Neuropharmacology Branch, National Institute of Mental Health, Bethesda, Maryland 20205
3. Department of Chemistry, University of Wisconsin, Milwaukee 53201
4. Laboratory of Bioorganic Chemistry, National Institute of Arthritis, Diabetes, and Digestive and Kidney Diseases, Bethesda, Maryland 20205